Methods have been developed for the preparation of millimolar amounts of oligosaccharides related to the blood-group substances. The nucleoside diphosphate sugars, acceptor monosaccharides, and the glycosyl transferases will be used to carry out a serial synthesis leading to the tri- and tetrasaccharides of the H, A and B blood groups. The component monosaccharides will be prepared with 13C enrichment and/or 2H at specific sites to permit the examination of solution conformations and of the interactions between the substrates and the glycosyl transferases. An attempt will be made using 13C and 1H-NMR to establish the conformation of the substrates in the active site of the galactosyl transferase from whey and of the ligands that are bound to soybean lectin. The metabolism of specifically 13C-enriched monosaccarides by bacterial and mammalian systems will be studied by NMR and GC-MS methods.